A. Field of the Invention
The embodiments of the present invention relate to a dual-mode hearing protector, and more particularly, the embodiments of the present invention relate to a manually switching dual-mode hearing protector.
B. Description of the Prior Art
A large part of the population is exposed to hazardous noise from time to time. This can be at work, while traveling, during leisure activities, or at home. The exposure can lead to permanent hearing loss, distract people's attention from other hazards, or simply cause stress.
In order to prevent both accidents and permanent hearing damage, hearing protection devices (“HPDs”) have been provided in many styles and over many years. It started with the earmuff that is still very relevant and addresses very noisy environments, e.g., airports, construction, shooting, or complex working/communication situations, e.g., fighter pilots.
Over the years, development of biocompatible soft materials has enabled soft earplugs in different styles and colors, as well as recent development of “one fits many” standard semi-soft earplugs in silicon-rubber type materials. For severe situations, the combination of an earmuff and an “in-the-ear” HPD is required to achieve desired attenuation. The physical limitation of hearing protection based on ear worn devices is defined where bone-conduction—body acoustics—becomes dominant at around 40 dB attenuation.
The in-the-ear styles mentioned are devices made to fit “the average” ear in one way or the other. Either the fit is provided by softness of the material leading to undefined device insertion and undefined attenuation, or the fit is provided by standard shaped structures intended to block off the ear canal. In both cases, the flat distribution of the individual shape of the outer ear and the ear canal leads to a bad fit, pressure points in the ear, and undefined positioning of the device.
To address this wearing comfort issue, in-the-ear hearing aid technology has been applied making customized ear molds with passive acoustical filter. These are long lasting devices with good wearing comfort. This customization process, however, is traditionally a very manual process creating varying results over time, low reproducibility, and the quality is very operator-skill dependent.
Customized earplugs are earplugs including a hard shell having an outer surface individually shaped according to the measured inner shape of the user's outer ear and ear canal. These earplugs presently are primarily used for housing hearing aids. The inner shape of the user's outer ear and ear canal may be measured, for example, by direct laser scanning or by forming an impression. The customized hard shell may be produced by an additive process, such as layer-by-layer laser sintering of a powder material.
On the other hand, soft earplugs are widely used, in particular also as hearing protection devices. A soft earplug has an outer surface with a standardized shape, and is made of a relatively soft material so that the outer surface of the earplug is capable of adapting its shape to the individual inner shape of the user's outer ear and ear canal.
It is commonly known to design hearing protection devices as so-called active hearing protection devices wherein each device is provided with an outer microphone for converting ambient sound into input audio signals, a signal processing unit for processing the input audio signals into output audio signals, and an acoustic output transducer, i.e., a speaker or receiver, converting the audio output signals into sound perceivable by the user when wearing the hearing protection device. Thereby the hearing protection device is provided with a communication function enabling the user to perceive ambient sound signals in a controlled manner even when wearing the hearing protection device in a noisy environment.
In order to provide for a selective communication function, i.e., in order to enable the user to perceive, for example, speech while suppressing undesired noise, it is known to provide the audio signal processing unit with the capability of assessing the sound picture and adapting filter and gain settings to the noise level dynamically.
Numerous innovations for hearing protection earphones have been provided in the prior art that will be described below, which are in chronological order to show advancement in the art, and which are incorporated herein by reference thereto. Even though these innovations may be suitable for the specific individual purposes to which they address, they each differ in structure, and/or operation, and/or purpose from the embodiments of the present invention in that they do not teach a manually switching dual-mode hearing protector.
(1) U.S. Pat. No. 5,355,418 to Kelsey et al.
U.S. Pat. No. 5,355,418 issued to Kelsey et al. on Oct. 11, 1994 in class 381 and subclass 72 teaches a frequency selective hearing protection device and method utilizing adaptive filtering to hinder transmission of frequency components in ambient sound above a preselected threshold level. Sound frequency components not above the threshold level, such as normal speech, are allowed to pass. Electrical analog signals produced by a transducer are converted to a stream of digital input signals. The digital input signals are applied to a digital filter, such as an FIR filter, implementing a time domain difference equation. As a result, digital output signals are produced, which are reconverted to analog output signals and applied to an actuator to produce audible sound. To adjust the frequency response to suppress gain at frequency components above the threshold, windows of input and output data signals are first assembled. Respective frequency domain transforms, such as fast Fourier transforms, provide spectrums representative of frequency component amplitudes. Any violator components exceeding the threshold level are distinguished and coefficient values of the difference equation are altered to suppress gain at those frequencies. Preferably, the coefficient values are readjusted to again allow the frequencies to pass if the threshold is not exceeded in a preselected number of subsequent digital input signals.
(2) U.S. Pat. No. 5,361,304 to Jones et al.
U.S. Pat. No. 5,361,304 issued to Jones et al. on Nov. 1, 1994 in class 381 and subclass 72 teaches a headphone assembly for an active noise cancellation system, having a rigid molded plastics shell with a rigid baffle dividing the shell interior into a front volume and a closed rear volume, both of which may be filled with an acoustic foam. The baffle has a central opening in which is mounted a headphone transducer. A seal cushion is disposed around the mouth of the shell to effect an air-tight seal against the user's head. The headphone transducer has two effective sound-radiating surfaces of different sizes, and may be constructed as a form of orthodynamic drive unit. In the latter case, the orthodynamic drive unit diaphragm may have two separate coils of different radial extents.
(3) United States Patent Application Publication Number 2001/0046304 to Rast.
United States Patent Application Publication Number 2001/0046304 published to Rast on Nov. 29, 2001 in class 381 and subclass 74 teaches an apparatus and method for providing controlled acoustic isolation within various forms of headsets. Manual and automatic mechanisms change the amount of acoustic isolation provided by the headsets. Sounds in the environment that the user wishes to be made aware of can be programmed into a set of stored sound selection characteristics. In response to correlation of the stored sound characteristics with sounds in the external environment, the headset decreases acoustic isolation by coupling signals from one or more external microphones to the audio conversion elements within the earpieces. Alternatively, the apparatus can respond to sounds to be blocked by increasing acoustic isolation. A manual control may be activated by the user to decrease acoustic isolation at their discretion.
(4) U.S. Pat. No. 6,801,629 to Brimhall et al.
U.S. Pat. No. 6,801,629 issued to Brimhall et al. on Oct. 5, 2004 in class 381 and subclass 72 teaches a noise attenuating system, including a core portion adapted to actively filter sound waves into various bands and passing only those bands corresponding to safe amplitude sounds to a wearer's ear canal. Unlike conventional active noise cancellation systems, active noise attenuation is accomplished without providing additional sound waves inversely to unsafe amplitude sound waves. Instead, unsafe amplitude sound waves are passively blocked and only safe amplitude sound waves are passed through to the wearer's ear canal.
(5) United States Patent Application Publication Number 2006/0045299 to Haussmann.
United States Patent Application Publication Number 2006/0045299 published to Haussmann on Mar. 2, 2006 in class 381 and subclass 328 teaches a hearing protection earplug, including a shell for being worn at least in part in the ear canal of a user. The shell has a sound passage extending from an outer sound inlet opening of the shell to an inner sound output opening adapted to acoustically connect to the user's ear canal. A noise attenuation button is provided at the outer end of the shell and is manually movable relative to the shell between a resting position in which the outer sound inlet opening of the shell is closed by the button and at least one communication position in which the outer sound inlet opening of the shell is at least partially opened by the button for enabling sound communication between the environment and the sound passage of the shell. The sound passage is designed so that it has a sound attenuation of less than 10 dB averaged over the audible frequencies. Also taught is a use of the earplug and a method for manufacturing the earplug.
(6) United States Patent Application Publication Number 2006/0140416 to Berg.
United States Patent Application Publication Number 2006/0140416 published to Berg on Jun. 29, 2006 in class 381 and subclass 72 teaches a hearing protection system, including a first and a second hearing protection device. Each hearing protection device includes an active unit including an acoustic input transducer for converting ambient sound into input audio signals and an acoustic output transducer for transforming filtered audio signals into sound perceivable by the user. At least one of the active units include an audio signal processing unit for processing the input audio signals into the filtered audio signals. The audio signal processing unit includes an analyzer module for determining the intensity of the input audio signals separately for a plurality of spectral classes, a judgement module for judging—depending on the determined spectral intensities of the input digital audio signals—which one of a plurality of predetermined criteria is presently fulfilled by the input audio signals, and a filter module having adaptive frequency and time domain filter settings—depending on the judgement made by said judgement module—for producing the filtered audio signals. The judgement module is adapted to detect close speech. The filter settings are selected by the judgement module so that the filter settings provide for a transparent mode if the judgement module judges that no noise is present, for a first attenuation mode if the judgement module judges that noise without close speech is present, and for a second attenuation mode if the judgement module judges that noise with close speech is present.
It is apparent that numerous innovations for hearing protection earphones have been provided in the prior art that are adapted to be used. Furthermore, even though these innovations may be suitable for the specific individual purposes to which they address, they would not be suitable for the purposes of the embodiments of the present invention as heretofore described, namely, a manually switching dual-mode hearing protector.